1. Field of the Invention
The present invention relates to a fiber-optic fault locating and mapping device and, more specifically, to the use of a signaling tool in combination with cable locating equipment to accurately identify a fault location.
2. Description of the Prior Art
A variety of technologies are currently available for troubleshooting cable problems, such as cable breaks or cable faults. Each of these technologies serves a specific purpose and enables a technician to locate and isolate faults. For example, cable-locating equipment is currently used to locate a cable that may have a fault. Fault-locating equipment is currently used to locate a fault in a cable. Operators are traditionally trained in either cable-locating equipment or in fault-locating equipment.
A variety of different types of cables are deployed in communication systems. Some of the most notable are twisted pair cables, coaxial cables, and fiber-optic cables. Cable-locating equipment and fault-locating equipment are each individually used to troubleshoot particular types of cable systems; specifically, both technologies are individually used to troubleshoot fiber-optic cables.
A conventional fiber-optic cable consists of a plurality of fibers surrounded by a protective layer. The fibers are often bundled together and the protective layer surrounding the cables includes a variety of protective materials including a metal sheath. In conventional cable-locating equipment, a tone is communicated on the metal sheath so that a technician in the field can locate the fiber-optic cable. Approximately, every 50 miles or so, a cable-locating box is deployed on the cable. A tone is generated and communicated along the metal sheath of the cable. The technician is able to use equipment to detect the tone and ultimately locate the cable.
When a cable may be damaged, if there is no physical damage above ground, a technician cannot visually locate the cable. In conventional cable troubleshooting, the technician may use a transmitting device to dial into a cable-locating box and turn on the cable tone. Once the cable tone is turned on and is emanating from the cable, the technician may sweep the area in the general location of the cable to locate the cable. The technician can locate the cable using the signature of the tone. For example, when there is sheath damage in the cable, the cable tone either stops after the location of the sheath damage or diminishes after the location of the sheath damage. As a result, based on the level of the tone, the technician is able to locate the sheath damage.
However, it should be appreciated that it may take a substantial amount of time to locate the general area that the tone is emanating from since the range of conventional systems is about 25 miles. To precisely determine a cable location may take a substantial amount of time requiring that the technician traverse large areas. This of course increases the amount of time required to locate the cable and results in longer outage times for customers.
Another technology used to troubleshoot cable problems is an Optical Time Domain Reflectometer (OTDR). An OTDR transmits a light signal down a fiber and then measures the reflected light. When a fault or termination point occurs in a fiber, the light reflects off of the fault or termination point. For example, the OTDR collects irregularities from the fiber through signals reflected back from the fiber after a pulsed signal is placed on the fiber. These irregularities are averaged and plotted and will show any imperfections in the glass. The lasers used in an OTDR have a very broad spectrum and will only show the worst irregularity. On the other hand, a narrowly spaced laser will show all irregularities (i.e., those that are valid faults and those that are not). Therefore, it is sometimes difficult to tune the lasers to get the optimum laser spacing and fault detection.
Geographic maps are created when fiber-optic lines are installed, but often they are not representative of the actual installation. The OTDR can be used to measure the linear distance of the fault based on the time it takes the reflected light to return to the point of origin. However, with current OTDR systems, it is difficult to relate the OTDR reading to a geographic location. As a result, it is difficult to specifically isolate the fault.
Thus, although there are a variety of technologies deployed for troubleshooting cables, a better system for troubleshooting cables is needed.